1. Field of the Invention
This invention relates to a photoelectric switch, and more particularly to a rotary type photoelectric switch which is operated by the clockwise and counterclockwise rotation of a shaft.
2. Discussion of the Related Art
There are well known photoelectric switches which contain a light emitting element, a light receiving element, and a light interrupting element slidably provided therebetween. Referring to a conventional photoelectric switch shown in FIG. 1, a push button 1 is pressed against a return spring 2, so that a movable piece 3 pulled by a coil spring 4 acts downwardly in a snap movement. A light interrupting element 5 coupled with movable piece 3 vertically passes down such that a window 6 of the interrupting element 5 moves to the point where a light emitting from an LED 7 is received by a photo-diode 8, thus completing a switch circuit. The switch circuit is broken by releasing push button 1.
However, as denoted by A to D in FIG. 1, many pivots and connections are required to perform such a snap movement, which causes wear or abrasion of contacting parts at such connections, shortening the life of the conventional photoelectric switch.